The present invention relates to rearview mirror assemblies for large vehicles and, more particularly, to exterior rearview mirror assemblies with actuators which provide for adjustment of the reflective element for use on large vehicles, such as trucks, semi-trucks, vans, and the like.
Conventional exterior rearview mirror assemblies for trucks, vans and other large vehicles include a support bracket, a mirror housing which is mounted to the support bracket, a reflective element which is supported by the support bracket, and mirror mounting posts which extend from the support bracket for mounting the mirror assembly to support arms or mounting brackets on the vehicle. In other mirror assemblies, the actuator may be mounted directly to the housing. More recently these large vehicle exterior rearview mirror assemblies also include electrically operated actuators which support the reflective element on the support bracket or housing and provide remote adjustment of the reflective element.
In such larger vehicles, the suspension systems are usually much stiffer and less resilient than on most passenger vehicles. Furthermore, many trucks and vans have diesel engines which exhibit high vibration levels. As a result these larger vehicles induce relatively high base-level vibrations in the exterior mirror assemblies which they carry. Often this vibration is amplified by the vibration characteristics of the mirror assembly itself and, further, by the less-than-rigid mounting arrangements for the mirror assemblies often associated with larger vehicles.
One component that has an impact on the vibration of mirror assemblies, in general is the actuator. Trucks and vans often have large reflective elements on the order of at least 50 square inches. With increases in the size of the reflective element, the size and weight of the actuator also increases. The increase in actuator weight is most significant in electric actuators. Electric actuators add significant weight to a mirror assembly, especially in these large mirror assemblies. Heretofore, these larger electric actuators also require special mounting arrangements. For example, actuators available from Eaton of Three Rivers, Mich. include three mounting holes which are centrally located on the base wall of the actuator housing rather than at the periphery of the housing. As a result, these mounting arrangements are relatively flexible. Furthermore, the manufacturers of the Eaton actuators require the actuators to be mounted on posts or bosses which project from the support bracket and require a minimum spacing between the base wall of the actuator housing and the support bracket. This requirement is designed to avoid deformations to the base wall when the fasteners, which secure the actuator, are tightened. Deformations in the actuator housing wall can lead to binding of the actuator. The larger actuators, therefore, exhibit significant vibration, and when coupled with the inherent vibration of trucks, semis, vans and other large vehicles, often result in unacceptable vibration levels in the reflective element.
Therefore, there is a need for an exterior rearview mirror assembly, especially for large vehicles, which provides for remote adjustment of the reflective mirror element while minimizing the inherent vibration characteristics of the mirror assembly so that acceptable vibration levels in the reflective element are maintained.
Accordingly, the present invention provides an improved, vehicular exterior rearview mirror assembly for vehicles, especially suitable for larger vehicles, such as heavy trucks, vans and the like. The vehicular exterior rearview mirror assembly of the present invention provides an actuator mount with improved stiffness and rigidity resulting in significantly reduced vibration and consequent image blurring in the reflective element. Further, the assembly has an increased natural frequency which prevents resonance in normal operating ranges of these vehicles to help stabilize the mirror. The reduced vibration also reduces stress on any mirror arms or supports which attach the mirror assembly to the vehicle.
In one form, the invention is a vehicular exterior rearview mirror assembly for large vehicles, such as trucks, which includes a reflective element, a support bracket, and an actuator mounting the reflective element to the support bracket. A mirror housing is secured to the support bracket. The electrical actuator includes a housing with a central portion and a peripheral portion extending around the central portion, with the central portion being mounted to the support bracket. The assembly provides bearing contact for at least a portion of the peripheral surface of the housing and the support bracket to reduce the vibration and improve the stability of the mirror assembly.
In one aspect, the bracket includes a mounting surface and a resilient member interposed between the mounting surface and the peripheral surface of the actuator to provide the bearing contact. For example, the resilient member may comprise at least one resilient pad, which is secured to the support bracket. Preferably, the resilient pad is secured to the mounting surface of the support bracket, for example by an adhesive. The resilient pad preferably comprises a cellular urethane or equivalent type material. In other aspects, the resilient member has a durometer in a range of 12 to 18 Shore O.
In further aspects, the support bracket provides bearing contact for at least 50% of the peripheral surface of the actuator, more preferably contact for at least 75% of the peripheral surface of the actuator housing, and most preferably contact for approximately 100% of the peripheral surface. In other aspects, the support bracket includes an enlarged medial portion which is at least as large as the peripheral surface of the housing to provide the bearing contact.
In yet other aspects, the electrical actuator housing includes a movable member which extends into the housing and forms a friction contact with the housing. The movable member provides adjustment for the reflective element, with the frictional contact dampening the vibration of the movable member and reflective element. The actuator also includes a biasing member to urge the housing into frictional engagement with the movable member to thereby enhance the friction between the movable member and the housing to further reduce vibration of the movable member and of the reflective element. For example, the biasing member may comprise a resilient ring, which extends around the actuator housing to urge the actuator housing into frictional engagement with the movable member. Preferably, the resilient ring comprises a rubber elastic ring.
In another form of the invention, an exterior rearview mirror assembly for large vehicles, including trucks and vans, includes a one piece casing, a support bracket which extends between and is secured to the opposing end walls of the casing, a reflective element, and an electric actuator which supports the reflective element in the housing. The electric actuator is supported to the support bracket and includes an actuator housing having mounting openings for receiving fasteners, which mount the actuator to the bracket, and a peripheral surface which extends around the mounting openings. The support bracket provides bearing contact with at least a portion of the peripheral surface to provide a rigid mounting with an electric actuator in the mirror assembly.
In one aspect, the support bracket includes a medial portion which is at least the size of the peripheral surface of the actuator housing. For example, the support bracket may include an adapter plate mounted thereto which provides the bearing surface for the actuator. The adapter plate may be formed from metal, such as cast aluminum or plastic. In other aspects, the bracket further includes a gasket for providing bearing contact with the peripheral portion.
According to yet another form of the invention, an exterior rearview mirror assembly for large vehicles, such as trucks and vans, includes a reflective mirror element having a reflective surface of at least 50 square inches, a support bracket which is adapted for mounting to a vehicle, and a mirror casing which is secured to the support bracket. The mirror assembly further includes an actuator which is mounted to the support bracket by a plurality of fasteners, with the reflective mirror element being supported by the actuator in the casing. The actuator includes an actuator housing with a peripheral surface extending around the fasteners, which mount the actuator to the bracket, with the support bracket providing bearing contact for at least a portion of the peripheral portion surface of the housing whereby the mirror assembly has reduced vibration and improved stability. The actuator may, for example, comprise an electric or manual hand set actuator.
In other aspects, the support bracket comprises an elongated truss-like support bracket and further includes an enlarged medial portion, with the enlarged medial portion providing the bearing contact. Preferably, the enlarged medial portion is sized at least as large as the peripheral surface of the housing.
Accordingly, the present invention provides a vehicular exterior rearview mirror assembly for vehicles including trucks, semis, vans and the like, which has reduced vibration and increased stability to provide clearer viewing images for the vehicle driver. The assembly includes an improved support bracket which provides a rigid support for the actuator thereby improving the rigidity of the actuator mounting and the natural frequency of the mirror assembly.